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Abstract

Lithium ion batteries are a critical component enabling many modern technologies, including portable electronics, hybrid electric vehicles and more. While interest in nanomaterials for lithium ion batteries has been growing in recent years, very few systematic studies have been carried out on controlled architectures to explore of the impact of nanoscale and mesoscale structure on the reaction mechanisms, kinetics and resulting rate performance in these electrodes. Here we utilize a combination of anodized aluminum oxide templates and atomic layer deposition to fabricate a variety of systematically variable electrode architectures. The structural control and electrode design are described in detail. Then, analysis of the rate performance, with a focus on distinguishing between diffusion and charge transfer limited reaction mechanisms, is carried out for two distinct electrode systems, focusing on different issues which face advanced electrode architectures. First, we analyze the impact of nanotube length in 1D structures to establish a quantitative understanding of the balance between the loss of capacity due to resistance increases and improvements due to surface area increases. Second, we analyze the impact of transitioning from arrays of 1D nanostructures to crosslinked electrode networks. While 1D alignment is often considered favorable for reducing defects that may lead to capacity loss and degradation, our results indicate that the 3D structures gain more from increased surface area and mass loading than they lose from the introduction of defects. This observation opens up opportunities for rationally designed advanced electrode architectures to optimize the performance of electrochemical energy storage devices in novel ways that are unavailable to conventional, particle based electrode configurations.